Effects of chronic paralysis of chick embryo by flaxedil on the development of the neuromuscular junction]

Chronic paralysis of Chick embryos by the cholinergic antagonist flaxedil blocks the subsynaptic accumulation of acetylcholinesterase but not the formation of acetylcholine receptor cluster. Flaxedil paralysis also causes an increase of the total muscle content of acetylcholine receptor without altering the half-life of the receptor protein. The spontaneous activity of the embryon therefore "shuts off" the synthesis of extrasynpatic acetylcholine receptor.     

Study of the mitotic activity during the preneoplastic period in the liver of rats treated by diethylnitrosamine (author's transl)]

The chronic administration of diethylnitrosamine in drinking water induces liver tumors in the rat. The preneoplastic period may be divided in two phases differing mainly in the loss of circadian control of mitotic activity in hepatocytes.     

Ultrastructural autoradiographic study of blast cells in the mouse thymus. Interest for radioleukemia research.

Ultrastructural autoradiographic studies of mouse thymic blast cells after H3 Tdr injection show that their fine nuclear structure is related to their position in the cell cycle. The variations in the composition of the subcapsular blast cell population during radiation-induced leukemogenesis indicate kinetic changes in thymic lymphopoiesis, which are probably due to the oncogenic process.     

Endogenous electric field around muscle fibres depends on the Na+-K+ pump

We describe here experiments which reveal a new physiological specialization in the endplate (synaptic) region of skeletal muscle fibres. Using a vibrating microelectrode which can detect small currents flowing in extracellular fluid, we have found that the membrane in the endplate region behaves as though a steady positive current is generated in this location. Current re-enters the fibre in the extrajunctional region. Further experiments show that this current is dependent on the activity of the sodium pump. The electric field created by this current may be important for long-term interactions between muscle and nerve.     

G protein-coupled receptor P2Y5 and its ligand LPA are involved in maintenance of human hair growth

Hypotrichosis simplex is a group of nonsyndromic human alopecias. We mapped an autosomal recessive form of this disorder to chromosome 13q14.11-13q21.33, and identified homozygous truncating mutations in P2RY5, which encodes an orphan G protein-coupled receptor. Furthermore, we identified oleoyl-L-alpha-lysophosphatidic acid (LPA), a bioactive lipid, as a ligand for P2Y5 in reporter gene and radioligand binding experiments. Homology and studies of signaling transduction pathways suggest that P2Y5 is a member of a subgroup of LPA receptors, which also includes LPA4 and LPA5. Our study is the first to implicate a G protein-coupled receptor as essential for and specific to the maintenance of human hair growth. This finding may provide opportunities for new therapeutic approaches to the treatment of hair loss in humans.     

Mutations in SEPT9 cause hereditary neuralgic amyotrophy

Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant recurrent neuropathy affecting the brachial plexus. HNA is triggered by environmental factors such as infection or parturition. We report three mutations in the gene septin 9 (SEPT9) in six families with HNA linked to chromosome 17q25. HNA is the first monogenetic disease caused by mutations in a gene of the septin family. Septins are implicated in formation of the cytoskeleton, cell division and tumorigenesis.     

Dietary fat and tissue cholesterol in female rats

Zusammenfassung Junge, ausgewachsene weibliche Ratten nahmen nach 8 Wochen fettreicher Diät mehr Fett auf als solche mit einer fettarmen Diät, aber gleichviel Kalorien. Bei Weibchen mit körperlicher Bewegung war der Cholesteringehalt des Blutes und des Gewebes höher als bei eingesperrten, sitzenden Tieren.

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Financial support for this study was provided by Nutrition Foundation Grant No. 383.